Pressure sensors are used in a variety of harsh environments. For example, in oil drilling operations, it is desirable to obtain pressure measurements at the bottom of the well hole being drilled. This requires pressure sensors capable of withstanding the extreme heat (greater than 225° C.) and pressure (greater 20 KSI) found at the bottom of these well holes, which can be over five miles deep.
In addition to withstanding harsh environments, these pressure sensors are required to provide highly accurate pressure measurements and operate over long periods of time with minimal drift. Such pressure sensors also need a small diameter footprint in that multiple sensors are needed in the tools used in down hole applications, for example. These pressure sensors also need long life and ruggedness because a failed sensor is very difficult to access if replacement is necessary, such as in down hole operations.
In conventional approaches, the pressure sensor devices employed typically fail to meet one or more of the foregoing requirements. For example, pressure sensors formed in silicon dies are typically mounted to glass pedestals using thermoelectric bonding technology. For high pressure, high temperature sensor devices using this configuration, the glass mechanical properties are not adequate to allow the stability and performance required of these devices.
Accordingly, there is a need for improved pressure sensors that operate successfully and have a long life under harsh environmental conditions.